I agree with your list, other than Estlin and perhaps Xiahou. You have identified most of the very useful 4*s and some of my favorites. For example, Nanael is a great choice. She's the new Fawn who for many of us while we were still too poor to buy enough Charles has been a staple in many colosseum/arena teams. In fact, I have a level 100 Fawn, who I refer to as SuperFawn!

One thing important to point out is that, as Abyss says, with 5* becoming so cheap, the 4*s are not really very useful for their stats/damage any more. However, they are still useful as filler in teams where you need low deploy cost units. 4*s tend to have lower deploy costs and when compared to higher * cards with same deploy cost you can usually find something faster in a 4* if that's important. This would include Colosseums, Battle Arenas (and the similar guild event) and when you are battling other players as in attacking their monster parade. If you are attacking another player and only have 25 dc and 30 dc units, their monsters might get by before you have a chance to deploy to all of your available slots.

Most of your choices are great. If you put them up against other units, even 5* WITH THEIR SAME DEPLOY COST they still shine! In that spirit, I add a few of my own choices:

Benedetta - magic - 10 dc - male boostHer low deploy cost is great when you need to deploy a male boost card quickly, such as when attacking another player.

Ibiza - magic - 15 dc - C speed - slowsWe now have other C speed mages now, and we have other 15 dc mages, but right now she is the only one mage with both C speed and low deploy cost. So, she might come in handy if we ever get a mage-only event where speed + dc. I know, very niche, but still.

Biance - melee - 10 dc - A speed - no skillBiance has no skill but in terms of a super fast 10 dc, if you can't afford Charles (or enough Charles) she can substitute in the lower ranks. Her arena hit is powerful for low dc+fast 4* And, frankly, this game does not have enough black characters so I like to lead her when it's OK to lead cards for fun instead of stats, just to promote a little color in the game

Others to consider: * Otrere is C speed melee with Area Attack and 15dc* Jiang Shi and Ronja are 4*s with Drain Attack. If we decide that's a great skill(?) they are currently the two cards in the game with drain attack and lowest deploy cost (Jiang Shi is 15 dc A speed, Ronja is 20 dc C speed) Not sure the skill would be worth including them instead of any of the other good filler choices, but worth keeping in mind.

Zenobia possibly? Iron wall is decent even on a 4* and she hits hard too.

Yes Zenobia should definitely be added to the list. She doesn't just hit hard, she has the highest arena attack of all 4* units.

I think Angela deserves to make the list too. S speed poison unit with a relatively high arena attack for her 15 DC.

Ibiza and Samantha have both C speed slow units with 15 DC that deal decent arena damage. If you have any 4*s on the first row in your Battle Arena team, you should consider swapping them for these girls, because they can hide safely from your opponents area attacks on the 2nd/3rd row. Not sure if they're awesome enough to make the list though.

dont forget Fawn! B speed with 10 DC, all of those are great. Also Naneal, same as Fawn and will lump in Olga and Furfur to good 4*'s because of 10 DC and C speed, the later being ok because of the range for BA's, great fillers.

With critical strike (arena skill) coming in the (near?) future, Scarlet might also be worth keeping as one of those filler 10 DC units. Her 200 range will set her nicely in the third row during battle arena much like Zafiro. Too bad she's a D speed though, so we'll have to see what critical strike actually does before deciding if she's worthwhile in battle arena. But on the plus side, she's dirt cheap

Zenobia possibly? Iron wall is decent even on a 4* and she hits hard too.

Yes Zenobia should definitely be added to the list. She doesn't just hit hard, she has the highest arena attack of all 4* units.

I think Angela deserves to make the list too. S speed poison unit with a relatively high arena attack for her 15 DC.

Ibiza and Samantha have both C speed slow units with 15 DC that deal decent arena damage. If you have any 4*s on the first row in your Battle Arena team, you should consider swapping them for these girls, because they can hide safely from your opponents area attacks on the 2nd/3rd row. Not sure if they're awesome enough to make the list though.

I can second this Zenobia is quite the annoyance if we have GA again. Our guild stumbled into a Bernhard + 2xZenobia defense the past event. One proc from any of these was enough to stop any of us smashing through

I always tell my newbie allies the NO.1 4* they need is Angela (shes better then a lot of 5* cheaper too)

her S speed and poison will help them get through most of the quests.

Fillers

NOTE fillers should be 10DC or a 5* will do the job better

Fillers change depending on the event melee are usually only good for colo where their KB and good speed will come in handy (From best to worst)

Fawn, NanaelTarte, OlgaChiffre,Caracol,Furfur

Special mention will go to Biance (A speed),

However in BA they are all almost useless as KB(and poison) only affects the unit hit and the die so quickly that you may end up losing due to having less units at end of battle. (BA2 was the exception due to there was almost no Area Attack units)

AS slow and high range are best for BA with fillers the best units become (from best to worst)

If it procs all units in the same row dont take damage from attacks for the duration of the skill level. I think AoE bypasses but i'm not sure.

Stops many 6* attackers dead. If you have multiple procs.

Uh, no.

While I admit I fast forwarded through all the fights in the Guild Battle, so it's *possible* it works different in Guild Battle than in regular BA fights, that isn't at all how Iron wall works. (and, from what I saw of fast forwarded battles, it didn't look like it behaved any differently in GB.)

In BA, your units are attacked shortest range to longest range, top to bottom. (i.e. if you have a 110 range unit at the bottom of your front row, and the rest of your front row is 130 range, he'll be attacked first even though he's at the bottom)

Iron wall has a chance of procing every time the unit with the skill is attacked. The odds of it procing are based on the level of the IW skill. It will only protect against that single attack. The different attacks from units with dual/triple/quad attack are treated as individual attacks. (which is why they are useful, 4 attacks increases the chances of at least one breaking through the IW) An Area attack, (which would typically damage an entire row) is successfully blocked if any of the IW units in that row succeed an IW check. (They are all being attacked by it, they all have a chance to negate it.) If any of them successfully proc on an AoE, then the entire front row is shielded from it.

If an attack procs poison, (and I believe knockback, slow, etc.) it will effect the IW unit (or the team) even if IW also procs, which is what makes poison skill also a decent IW killer.

While I admit I fast forwarded through all the fights in the Guild Battle, so it's *possible* it works different in Guild Battle than in regular BA fights, that isn't at all how Iron wall works. (and, from what I saw of fast forwarded battles, it didn't look like it behaved any differently in GB.)

In BA, your units are attacked shortest range to longest range, top to bottom. (i.e. if you have a 110 range unit at the bottom of your front row, and the rest of your front row is 130 range, he'll be attacked first even though he's at the bottom)

Iron wall has a chance of procing every time the unit with the skill is attacked. The odds of it procing are based on the level of the IW skill. It will only protect against that single attack. The different attacks from units with dual/triple/quad attack are treated as individual attacks. (which is why they are useful, 4 attacks increases the chances of at least one breaking through the IW) An Area attack, (which would typically damage an entire row) is successfully blocked if any of the IW units in that row succeed an IW check. (They are all being attacked by it, they all have a chance to negate it.) If any of them successfully proc on an AoE, then the entire front row is shielded from it.

If an attack procs poison, (and I believe knockback, slow, etc.) it will effect the IW unit (or the team) even if IW also procs, which is what makes poison skill also a decent IW killer.

Oh, and it's not a unit, but Stray Cat (M) is worth keeping

I may have noticed wrongly then hmm. From what i observed after every proc the first Unit took no damage from multiple unit attacks before it got damaged again. I assumed it simply blocked up to the IW skill count before it could be damaged again. I was fast forwarding through most of my battles but i definitely recall seeing something of that nature. It makes sense that each unit procs once though You've been playing much longer than me I'll take your word for it.